Vigilancia Tecnológica

Excessive exposure to noises, which corresponds to unwanted and/or unpleasant sounds, poses as a threat to people’s health and can cause irritability, insomnia and even hearing loss. To attenuate noises, sound absorbers usually composed of porous materials are widely used. These, which appear as large networks of interconnected pores, are capable of absorbing medium and high sound frequencies, specially, transforming into heat the majority of the sound energy that reaches them. Such dissipations occur due to viscous, thermal and inertial losses resulted from interactions between the solid and fluid phases from which the porous materials are composed of. With the growing demand for acoustic comfort, one of the most important topics in noise control engineering is currently the search for sound absorption materials that provide attenuations in wide frequency ranges with minimum cost, weight and thickness. Fiberglass wool and melamine foam are widely used, and a variety of new porous materials are being developed, such as polymer micro- and nanofiber mats obtained by electrospinning. It is here investigated the acoustic potential of the electrospun polycaprolactone (PCL) fiber mat, normally used as a biomaterial. The sound absorption capacity of a material is given by its sound absorption coefficient (?), while its sound insulation capacity is denoted by its transmission loss (TL), and these are normally conflicting. In an impedance tube, through the transfer function and the transfer matrix methods, ? and TL curves are here determined for samples of fiberglass wool and melamine foam with 25 mm width, and later these combined with a layer of approximately 0.3 mm of PCL fiber mat. With the addition of a fine layer of those polymeric fibers to both base materials, it was observed expressive gains in the sound absorption and transmission loss potentials in almost all the totality of the frequency range analyzed, which extends from 400 to 2500 Hz. It was also analyzed the morphology of the study materials through Scanning Electron Microscopy (SEM), and their porosities were determined through an optical approach with the aid of X-ray microtomography.